The present invention relates to cosmetic preparations, particularly to skin care products, shaving preparations, and depilatory preparations (xe2x80x98lady shavingxe2x80x99 preparations), which protect skin from mechanical irritation. The active agent contained in the preparations is trimethylglycine. The invention also relates to the use of trimethylglycine as a skin-protecting agent in different cosmetic preparations, and to a method of protecting skin from mechanical irritation.
Skin is subjected to mechanical irritation, i.e. it is scratched, abraded, chafed or cut, in many situations. When men shave, a razor or the blade of a shaver may scratch or cut. the skin on the face despite the use of shaving lather or shaving soap. Women, in turn, cut hair off the legs, armpits, and groin, where the skin is extra sensitive, and the treatment easily scrapes or cuts the skin. Infants and persons using incontinence diapers have the problem that their skin often moistens and thereby becomes thinner, and the diaper chafes and damages the skin. Shoes, in turn, abrade the skin on the heels, ball of the foot, and toes, and the skin on the hands is easily abraded and scratched in agricultural and garden work.
Cut, sore skin aches, smarts, and feels tight; microwounds are subjected to inflammation; and application of common cosmetic preparations to the skin does not necessarily ease the discomfort, nor protect the skin. On the contrary, application of a preparation on cut, sore skin often adds to smarting and skin irritation.
The object of the present invention is to provide a preparation protecting skin from mechanical irritation.
Another object of the present invention is to provide a method of protecting skin from mechanical irritation.
Surprisingly, it has been discovered that trimethylglycine protects skin from cutting, scratching, abrasion, chafing, and other mechanical irritation, and so trimethylglycine can be used in different cosmetic preparations as an agent protecting skin from such irritation. The present invention thus relates to the use of trimethylglycine as an agent protecting skin from mechanical irritation in cosmetic preparations, particularly in skin care products, shaving preparations, and depilatory preparations. The present invention also relates to a cosmetic preparation that contains trimethylglycine as an ingredient protecting skin from mechanical irritation. The present invention further relates to a method of protecting skin from mechanical irritation by applying a trimethylglycine containing cosmetic preparation to the skin.
In the present invention, mechanical irritation means external damage caused to epidermis by different objects, such as a shaver blade, a razor, shoes, a diaper, clothes, tools, or the like. A cosmetic preparation here means different skin care products, such as skin creams, cleansers, tonics, and milks; hand creams; foot care products, such as foot creams, and foot baths; shaving preparations, such as after-shave lotions, shaving lathers, foams, gels, and balms; depilatory preparations; products of personal hygiene (xe2x80x98lady-shavingxe2x80x99 preparations), and the like. Preferred preparations according to the invention are foot care products, after-shave lotions, skin tonics, and baby care products.
In the present invention trimethylglycine means a naturally occurring quaternary ammonium type compound having the formula 
which is present as an anhydride or a monohydrate. The compound is commonly also called betaine, trimethylammonioacetate, 1-carboxy-N,N,N-trimethylmethaneaminium, inner salt, and glycine betaine. In the pure form, it is a white, crystalline compound that is readily soluble in water, and in lower alcohols, such as methanol and ethanol. In plants it functions as an osmolyte and thereby protects cells from the effects of osmotic stress.
Trimethylglycine has a bipolar structure, and it contains several metabolically reactive methyl groups, which it can donate in enzyme catalyzed reactions. Most organisms are able to synthesize small amounts of trimethylglycine, e.g. for the methyl donor function, but are not able to produce it, nor store it, in large amounts.
At cell level, trimethylglycine has been observed to protect plants particularly under stress conditions. It has been used as an agent improving the preservation characteristics of a plant, and as an agent improving the drought and chill resistance of a growing plant. To enhance growth, trimethylglycine has also been added to fertilizers. Further, trimethylglycine has been used as an additive in animal feed or fodder. It has also been observed to have pharmacological activity, e.g. it prevents detrimental effects of coccidiosis in broilers.
Synthetic long-chain alkyl ester, sulpho, and aluminium salt derivatives of trimethylglycine, commonlyxe2x80x94and slightly misleadinglyxe2x80x94called xe2x80x98betaine derivativesxe2x80x99 or xe2x80x98betainesxe2x80x99, have long been used as amphoteric surfactants in cosmetic industry, that is, e.g. as foaming agents in shampoos, soaps, and cleansers. As examples are mentioned U.S. Pat. Nos. 4,490,355 and 4,654,161. Trimethylglycine, instead, is not useful in the above-mentioned cosmetic applications, since its surface activity is completely different, and since it does not foam at all.
The surprising effect of trimethylglycine presented in the invention, i.e. that it protects skin from mechanical irritation, has not been described earlier, although trimethylglycine has been used for other purposes in cosmetic industry. EP 531,387 teaches that a preparation containing trimethylglycine reduces irritation caused by skin-irritating ingredients of a cosmetic preparation, such as cationic compounds, quaternary ammonium compounds, solvents, surfactants, and aseptic agents. EP 56,595 teaches a hair conditioning composition that contains 0.1 to 25% by weight of betaine, and 0.1 to 10% by weight of aliphatic organic acid, such as citric acid, and is stated to act as a hair conditioner, an antioxidant, and a buffer. German Patent 1,911,144 teaches a skin care composition that contains urea and lactic acid, and a cream base that can contain amino acid derivatives, such as betaine.
Trimethylglycine hydrochloridexe2x80x94since it is strongly acidicxe2x80x94differs in its characteristics from trimethylglycine anhydride and trimethylglycine monohydrate, has also been used in cosmetic products. Hungarian Patent T50,622 teaches a skin care composition that contains e.g. 0.3 to 0.6% of betaine hydrochloride.
EP 2,127 describes a shaving composition containing xe2x80x98cosmetically acceptable betainexe2x80x99, which means particularly long-chain alkyl esters of glycine, the composition being stated to affect the root of a hair, so that the hair can be cut as close to the skin as possible, which improves the shaving result.
The best known organisms producing large amounts of trimethylglycine are plants of the genus Chenopodiaceae, such as sugar beet, and some microbes and marine invertebrates. It can be obtained e.g. from sugar beet by chromatographic methods. Trimethylglycine is commercially available both as an anhydride and as a monohydrate from Cultor Oy, Finnsugar Bioproducts.
A cosmetic preparation according to the present invention protecting skin from mechanical irritation contains 0.1 to 20% by weight, preferably 2 to 10% by weight, particularly 2 to 6% by weight of trimethylglycine as an anhydride or as a monohydrate in an aqueous composition or cream base, which may be e.g. an oil-in-water or a water-in-oil emulsion, water, or a water/alcohol mixture. The preparation also contains ingredients and additives that are commonly used in the cosmetic preparation concerned. They may be, for example, skin care agents, softening agents, astringent agents, refreshing agents, anti-oxidation agents, emulsifying agents, viscosity increasing agents, moisturizing agents, stabilizing agents, colouring agents, perfumes, surfactants, and the like, as well as alcohols and/or water.
The cosmetic preparations according to the invention include, in particular, skin care products, shaving preparations, depilatory preparations, and products of personal hygiene, such as skin tonics and milks; skin creams and lotions; cleansing creams, milks and gels; liquid cleansers; foot creams and baths; hand creams; refresher and moisturizing tissues and sprays; after-shave lotions; shaving lathers, gels and balms; and foam preparations. The preparation type is selected according to the need. The preparations of the invention can be formulated by common methods well known to those skilled in the art.
The use of trimethylglycine in the above preparations provides the products with characteristics that protect skin from mechanical irritation. As trimethylglycine also reduces the effect of any irritating agents contained in the cosmetic preparation, as described in EP 531,387, preparations containing trimethylglycine can be regarded as being particularly friendly to the skin.
It has been observed that trimethylglycine protects skin from mechanical irritation particularly effectively when it is applied as close as possible to the moment when the epidermis is cut, i.e. almost at the very moment that the damage is done. In the method of the invention for protecting skin from mechanical irritation, a preparation according the invention can thus be applied to the skin at the very moment that the skin is subjected to irritation, or even before it. For example, when one wants to protect the skin from being cut and scratched by the blade of a shaver during shaving or cutting off of hairs, a preferred preparation according to the invention might be a shaving lather or foam, to ensure that skin-protecting trimethylglycine is immediately present on the skin. If the preparation according to the invention is an after-shave lotion or a skin tonic, it will be applied to the skin immediately after shaving or cutting off of hairs. When one wants to protect the skin from being chafed by a diaper, a cream according to the invention can be applied to the skin before putting on a new diaper, or the skin can be washed or wiped with a cleanser or a moisturizing tissue according to the invention. Foot or hand creams according to the invention can be used according to the need for symptomatic alleviation of irritation, or for preventing irritation.